


The Hound of the MacLeods

by BluePhoenix73



Category: Castle, Supernatural
Genre: Alternate Universe, Alternate Universe - Canon Divergence, Breaking the Fourth Wall, Crossover, Friendship, Gen, Male-Female Friendship, Meta, Parallel Universes, References to Castiel/Other(s), references to other characters played by the actors, unlikely friendship
Language: English
Status: Completed
Published: 2017-08-11
Updated: 2017-08-11
Packaged: 2018-12-13 05:00:03
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 9
Words: 15,421
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/11752545
Author URL: https://archiveofourown.org/users/BluePhoenix73/pseuds/BluePhoenix73
Summary: The supernatural doesn't really exist in Kate Beckett and Richard Castle's New York, so when a hellhound gets loose and kills someone in Manhattan, Crowley, the King of Hell himself, calls on Sam and Dean Winchester to track it down and bring it back to him.A reinterpretation ofCastleepisode 7.03 "Clear and Present Danger"... with a littleSupernaturaltwist. Rated "T" for language and mild violence.





	1. Chapter 1

**Notes for the Chapter:**

> Hi there! Thanks for checking this out! I know this is a crossfic and that that can get a bit confusing, so I tried to kind of introduce anyone who isn't really in one fandom or the other to the characters of the other fandom. Just in case, though, here are our main characters from each show (that are relevant to this story): 
> 
> **[Supernatural](http://supernatural.wikia.com/wiki/Supernatural):**  
> [Sam Winchester](http://supernatural.wikia.com/wiki/Sam_Winchester)  
> [Dean Winchester](http://supernatural.wikia.com/wiki/Dean_Winchester)  
> [Crowley](http://supernatural.wikia.com/wiki/Crowley) 
> 
> **[Castle](http://castle.wikia.com/wiki/Castle):**  
> [Kate Beckett](http://castle.wikia.com/wiki/Kate_Beckett)  
> [Richard Castle](http://castle.wikia.com/wiki/Richard_Castle)  
> [Javier Esposito](http://castle.wikia.com/wiki/Javier_Esposito)  
> [Kevin Ryan](http://castle.wikia.com/wiki/Kevin_Ryan) 
> 
> Hope that helps! Have fun!

An ominous wind blew through Lebanon, Kansas, as Sam and Dean Winchester enjoyed a day off in the Men of Letters bunker, the underground stronghold they called home. Sam was seated at the usual table in the main room, poring over his laptop, scouring the internet for a light case in the area. To his side, Dean grossly devoured a sandwich, his pure ecstasy obvious in the disturbing sounds he was making. 

“Hey, could you knock it off?” Sam said, not bothering to look at his brother. 

“Why? Weren’t you the one who said I needed to take it easy?” 

Sam rolled his eyes. “I did, but I’ve been looking for something lighter, something—” 

“You remember how that turned out last time, Sammy.” 

“I think a school play about our lives and an angry Muse is a once-in-a-lifetime thing, Dean.” 

Dean shrugged. “We’ve seen some weird shit. Didn’t think it could get weirder, but then that happened.” 

“You… have a point actually.” Sam looked up as his brother slurped condiments from his fingers. “Do you two wanna get a room?” 

“I offered to make you something. You decided to stick with… whatever that thing is.” He gestured toward the granola bar in Sam’s hand. 

“Yeah, still good, thanks.” 

As Dean was going in for another monstrous bite, he heard a soft _whoosh_ , and felt watched. 

“Cas?” 

“Guess again, Pumbaa.” 

Dean looked over his shoulder at Crowley standing stone-faced behind him. 

“I see the appetite hasn’t worn off since we parted ways,” he said, wandering around to the side of the table opposite Sam. “You and Timon busy?” 

“What do you want, Crowley?” Sam asked. 

“I have a… favor to ask,” he said, looking down at tented fingers. 

“You? Asking a favor of _us?_ You _must_ be desperate,” Dean said, raising his sandwich to his mouth. 

With a snap, the meal was in Crowley’s hand. Dean glared at him. 

“How did you get in here, anyway?” Dean growled. 

“Plot convenience,” Crowley answered nonchalantly, taking a bite of Dean’s sandwich. 

“What?” Sam said. 

“Anyway, I’ve found myself backed into a rather tight corner,” Crowley continued. “See, there’s been an incident. One of my hellhounds got loose, can’t track her down on my own. Too busy.” 

“So you want us to do it?” Sam asked. “Why would we be interested in this?” 

“Because Ophelia didn’t just run off. No, that would’ve been easy, I could’ve sent any old lackey to bring her back. She—” 

“Hang on, Ophelia?” Dean said. “What is it with you and your Shakespeare names?” 

Crowley and Sam both stared at him, dumbfounded. 

“What?” Dean said, reaching for his beer. “I read.” 

Crowley raised a skeptical eyebrow. Dean rolled his eyes. 

“Fine,” he sighed. “I watched a porn parody of Hamlet once. Happy?” 

“Quite,” Crowley said as Sam buried his face in his hands. “As I was saying, Ophie found her way into a dimensional portal. She’s loose in New York, but it’s a very different New York from the one you and I know.” 

“You’re saying she’s in a different dimension?” Sam said. 

“You always were the smart one, Moose.” 

“How is that possible?” 

“Maybe it’s like that time Gabriel sent us into that… _place_ ,” Dean said, looking as though he’d just smelled something putrid. “You were married to Ruby, and they put me in _makeup_.” 

“Right, but an archangel did that,” Sam said. “You’re saying there are doors to these other places just out in the open?” 

“Not out in the open, no one’s going to walk into one by accident,” Crowley said. “One of my demons was sneaking around where he shouldn’t have been. He’s been taken care of.” Sam and Dean exchanged looks. They knew what that meant. “But Ophie followed him and got through the door.” 

“So you want us to go through this door and find your pet?” Dean asked. “How do we know it’s even going to be open when we try to get back?” 

“Ophie’s a good girl. I want her back. Besides—I have a reputation to keep.” Dean looked confused. “You’ll see when you get there.” 

“When we get where?” Sam asked, closing his laptop. 

“New York, of course.” 

“But, _where_ in—” 

“Sorry about this, Moose,” Crowley interrupted, tapping Sam on the head in much the same way angels did to render people unconscious. Sam slumped over on the table, and he turned to Dean. 

“Dude, you could’ve at least let me finish my sandwich,” Dean said with a sigh. 

“Maybe next time,” Crowley said. “Can’t have you two knowing where this portal is.” 

“Fine, let’s get this over with.” 

Crowley reached over to tap Dean’s forehead, but instead pulled back and punched him with every ounce of strength he could muster. Dean was knocked to the ground, out cold from both the punch and Crowley’s magic. 

“Well,” the King of Hell said, shaking his hand out. “That went better than expected.” He gripped both Winchesters by their shirt collars and disappeared from the bunker, as quickly as he’d arrived.

**Notes for the Chapter:**

> Info on the Men of Letters bunker [here](http://www.supernaturalwiki.com/index.php?title=Men_of_Letters_Bunker) in case you need it. ;)


	2. Chapter 2

Sam awoke to the sound of traffic. His head felt heavy, and there was a dull throb right between his eyes. He blinked hard and looked around: he was in a hotel room, somewhere, in the early evening. Two queen beds—Dean face down on the one closer to the door—a mini fridge, a microwave. The closet door was open, and their suits hung neatly inside it. Also open was the door that would have joined this room with another, though there was _not_ a hotel room on the other side. Crowley leaned against the doorframe, a smirk on his face. 

“I wondered which of you was going to get up first,” he said. “About time, too: hell’s not going to run itself.” 

Sam rubbed his forehead and stood up. “Are we—?” 

“In the other dimension I told you about? Yes,” Crowley nodded. 

“Is this the only other… _world_ out there?” 

Crowley scoffed. “Is there only one other planet in the solar system?” 

Sam’s eyes widened. “There are that many? How did this escape the Men of Letters?” 

“They’re very well-hidden. Some of them have been closed. Others opened. Not always in the same places. Like this one.” Crowley rapped his knuckles lightly against the doorframe. “So, Moose, here’s the deal. You have those fancy glasses you use to see my dogs. They’re downstairs. This…” he produced a whistle from his pocket and handed it to Sam. “Should help you, as well. You and that brother of yours get the job done and come back here. Knock on this door three times and I’ll let you in. Deal?” 

Sam nodded. “I think so.” 

“Good. Need to practice my American accent: I have a Doctor appointment.” Crowley began to close the door behind him. “Bye, boys.” The door closed and bolted, and Sam turned around. Dean was stirring on the bed. 

“Sam?” he said, rubbing his eyes. 

“Yeah, I’m here,” Sam said. “I don’t quite know where ‘here’ is, but I’m here.” Sam fished his phone out of his back pocket and turned it on. “Well, at least I’ve got a signal.” He turned on the GPS and looked up a map. “Looks like we’re in Manhattan, Lower East Side.” 

“What’re we doing there?” 

“Beats me,” Sam said. “We don’t really have any—” Sam was cut off by an alert on his phone. A news story. “Leads,” he finished, tapping the notification and skimming the blurb. 

“What is it?” Dean asked, sitting up and gingerly touching the spot where Crowley had punched him, which was turning an angry shade of red. 

“Murder,” Sam said. “Guy was murdered in his apartment. They’re calling it an animal attack, but no animals were allowed in the building.” 

“So?” Dean was at the bathroom mirror, examining his new mark. 

“He was ripped to shreds, Dean,” Sam said. “Unless a bear managed to get into a New York City apartment building, I think we might have a lead on our hellhound.” 

“Great, so where’re we headed?” 

“Not this apartment. Interview says the guy usually hung out at a place called Chelsea Billiards.” Sam looked up from his phone. “I doubt Ophelia would’ve gone after him without a reason. Maybe we should check it out?” 

Dean shrugged. “Your guess is as good as mine. Time to suit up.”

 

* * *

 

NYPD Detective Kate Beckett and her partner, mystery novelist Richard Castle, had followed a trail of clues leading from the apartment of their victim, Will Fairwick, to one of his regular hangouts, Chelsea Billiards. With a flash of her badge, Beckett secured the cooperation of the manager, one Fats Shepherd. This was one of the more upscale clubs in the area, but she knew that some of the shadiest schemes came out of places like these. Her killer could be any one of these people. 

“Will Fairwick was a regular at the pool tables here?” she asked Shepherd. 

“Yeah, Will worked my tables. He was the best I’ve ever seen,” he replied. “Knew all the angles.” 

“Anyone he took for money ever have a problem with him?” 

“Sure, but Will mostly hustled Wall Street tools for ten bills a game.” Shouting erupted behind them at one of the pool tables, where it looked like someone had done just that. “Losing a grand here and there, that’s chump change for them. None of those guys would ever kill Will over a bet.” 

“But there are guys that would?” Castle chimed in, plots already forming in his head. 

“Will always worked the upscale clubs like mine where it’s safe to take money off the clientele. But recently I heard that he started hustling out in Brooklyn. At O’Neil’s. That place is full of felons and low-lifes.” 

“Any idea why he decided to move his game up there?” Beckett asked. 

“Well, it wasn’t for the money. I mean, he was cleaning up here. But uh… what people say and do doesn’t always make sense.” 

“Mr. Shepherd—” Beckett began. She was interrupted by two intimidatingly tall men approaching, both in tailored suits. They flashed FBI badges at Shepherd and at her. 

“Agents Stanwyk and Babar,” the one with the shorter hair—probably Agent Stanwyk—said as he flipped his badge closed and slid it into an inner pocket. 

“We’re here investigating the murder of Will Fairwick,” the other said, his tone more gentle even as he talked over the commotion of the club. 

“I’m Detective Beckett, NYPD,” Beckett said, brandishing her own badge and reaching out to shake their hands. 

“And I’m Rick Castle, mystery writer,” Castle added with a grin, shaking the agents’ hands after Beckett. “I’m sure you’ve heard of the _Nikki Heat_ series.” 

“Can’t say I have,” Stanwyk said. 

Castle looked taken aback. “No? _Derek Storm_?” 

“Derek what?” 

“My partner doesn’t read much,” Babar cut in, noticing Castle’s hurt expression. 

“So,” Beckett said over crossed arms. “Why would the FBI be stepping on _my_ case?” 

“I’m sorry ma’am,” Stanwyk said. “That’s classified.” 

Beckett glanced at Castle. His brow was furrowed, like his mind was racing. Usually he’d be like a kid on Christmas if the FBI actually got involved in one of their cases, but something was off. It might have just been his bruised ego, but she was sure this went deeper. 

“Well, I’m sure you’d like to hear the rest of our interview with Mr. Shepherd,” Beckett said, her eyes narrowing slightly. 

“Please,” Babar nodded, turning his attention to Shepherd. 

“Well, as I was telling Detective Beckett,” Shepherd said, looking up at the two agents towering over him. “Will recently started hustling pool out in Brooklyn. I don’t know why he got it in his head to go there: it’s the image of a seedy dive bar. But he said… ah, never mind, it’s probably stupid anyway.” 

“I assure you, sir, we’ll hear whatever you have to say,” Stanwyk said. 

“Nothing’s stupid if it could help us fill in the blanks on Will’s life,” Beckett added. 

Shepherd hesitated and glanced between all of them. “I once asked him how he got to be so good. He told me he ‘went down to the crossroads and made a deal with the devil’ for his talent.” Out of the corner of her eye, Beckett saw the agents exchange a knowing glance. “I figure, that’s gotta be a joke, right? But the other night, well, he looked nervous. I mean, downright scared. So I asked him, I said, what’s going on? You know what he told me?” 

“No, but I want to know,” Castle said, clearly taken in by Shepherd’s tale. Beckett resisted rolling her eyes. 

“He said it wasn’t a joke. He said his time was up. That he was about to lose his soul.” Castle was breathless, perhaps even—shockingly—speechless. After a dramatic pause, Shepherd let out a hearty laugh, startling him back to attention. “Like I said though, stupid, right?” 

Shepherd returned to work, and for a long moment, Beckett and Castle looked at each other in silence, as did the agents. Beckett’s phone buzzed, and everyone focused their attention on it. 

“Espo’s got something for us at the precinct,” she said, stashing it back in her pocket. She made eye contact with each of the agents. “You’re welcome to accompany us, too, Agents. We’re at the Twelfth. Meet you there.” 

“Thank you, Detective,” Babar nodded as Beckett led Castle from the club.

**Notes for the Chapter:**

> Crowley needed to be meta in this one. He connects their worlds. It's a beautiful thing.
> 
> P.S.: Info about the [12th Precinct](http://castle.wikia.com/wiki/12th_Precinct) as it appears in _Castle_.


	3. Chapter 3

**Notes for the Chapter:**

> Info on medical examiner ("M.E.")/Beckett's best friend [Lanie Parish](http://castle.wikia.com/wiki/Lanie_Parish).

“How could they not know _Nikki Heat_?” Castle insisted when they reached Beckett’s cruiser. “It’s the biggest thing since… well, since _Derek Storm_!” 

“You looked like you were thinking about something back there,” Beckett commented, securing her seatbelt. “Something on your mind, Castle?” 

“Aside from their obvious ignorance of literary brilliance?” 

“And your bruised ego.” 

Castle sighed. “I can’t help but think I’ve heard their names somewhere before.” 

Beckett looked over at him. “Friends of yours?” 

“No, it’s not that. I don’t know _them,_ I know their names.” Castle waved his fingers next to his head, like he was trying to draw out a long-unused memory. “I just can’t—” 

Beckett clapped a hand over his mouth. “Ssh, here they come.” 

They watched in silence as the two men got into a classic car. In the darkness, neither could quite make out the make or model, but it didn’t seem like an FBI standard-issue vehicle. 

“What kind of FBI agent drives a car like that?” Beckett wondered aloud. From the passenger seat, Castle made a muffled whining sound, and she removed her hand from his mouth. “Sorry.” 

“That can’t be any later than 1980,” Castle observed. “They might not know books, but these guys are officially _awesome!_ ” 

Unamused with her fiancé’s fascination, Beckett started her car and headed for the precinct. Whoever these guys were, they weren’t getting in the way of her investigation.

 

* * *

 

“You think our hellhound was collecting on a deal?” Sam asked as Dean drove toward the 12th Precinct. 

“Nah, Crowley wouldn’t send us here for that,” Dean said before cursing at a driver who cut him off. “Stupid New York traffic.” 

“Maybe we should consider taking the subway next time?” Sam suggested. 

“And just leave Baby at the hotel? No, no, I could never do that.” 

“Dean, this isn’t even our… _world_ ,” Sam said, trying to find the right words. “This isn’t really our car.” 

“Don’t listen to him, Baby,” Dean cooed, caressing the steering wheel with his hand. “He doesn’t know what he’s talking about.” 

Sam rolled his eyes. “Maybe lay off the _Fletch_ references for a while though, okay?” 

“Hey, I let you be Babar this time.” 

“Whatever.”

 

* * *

 

“A guy says he’s going to lose his soul and then he dies? How creepy is that?” Castle said when he, Beckett, Sam, and Dean met up at the 12th Precinct. Detectives Kevin Ryan and Javier Esposito, partners themselves and integral to Beckett’s team, were waiting for them at the station’s bullpen. 

“A guy was hustling felons and got himself killed. That’s not creepy, that’s probable cause.” Beckett glanced at Ryan. “Anything on our vic’s employer?” 

“Uh, yeah,” Ryan replied absentmindedly. “I got a 1-800 number for Greenblatt Insurance, but they’re closed until tomorrow.” 

Beckett pursed her lips. “Can you stop by O’Neil’s Bar in Brooklyn on your way home? Ask around about Fairwick?” 

Ryan checked his watch nervously. 

“Unless Jenny needs you,” Beckett added. Sam spotted a ring on Ryan’s left hand: Ryan was a family man. 

“No, all good,” Ryan said with a reassuring smile. He threw a wave to Esposito and the others as he headed for the door, and the five remaining returned to the case. 

“Anything else about Fairwick?” Sam asked, following Esposito into a workroom. 

“I pulled security footage from Will’s building,” Esposito said. “There’s a security camera in the elevator area slightly angled toward Will’s apartment.” 

Sam nodded in approval as Dean eyed the Precinct’s tech guru, Tory. Her attention was glued to the monitor in front of her. 

“I was able to magnify the footage,” she said, tapping the keyboard a couple of times. 

“Great. Then we should be able to pull an image of our killer leaving the apartment,” Beckett said, surveying the monitor. 

“You’d think so,” Dean said, focusing on the screen instead of Tory’s rear. “Ain’t always that easy.” 

“Agent Stanwyk’s right,” Esposito said. “Watch.” 

The room was silent as they all watched Fairwick step out of his apartment and look around. He then barreled back into his apartment, terrified, not bothering to close the door behind him. 

“This is a minute before the neighbors downstairs called 911,” Esposito said. 

“And this is minutes later,” Tory said, tapping another key. The image shifted, showing the door mostly closing in a jerky motion. 

“The door closes on its own,” Esposito commented, “and all the windows in Will’s apartment were locked from the inside. No one enters or leaves the apartment until the police arrived.” 

“That’s impossible,” Beckett breathed. “The killer has to be on that footage somewhere.” 

“He is,” Castle said, drawing a look from everyone in the room. “Will made a deal with the devil and the contract was up, so it was time to pay. The devil came and got his due.” 

Beckett led the boys back toward her desk and their “murder board,” a whiteboard where she kept the case’s details organized. 

“So how does this explain this mysterious ‘animal attack’?” Dean asked as he leaned against a wall, pretending to go along with their theories. 

“Hellhounds…” Castle muttered in a sing-song voice, not-so-under his breath. 

Beckett sighed. “Easy. The killer was perfectly human. Will didn’t close the door when he ran back inside because he saw our killer come in through a window. The killer must have shut the door from inside before they slipped out the same way they came in.” 

“Didn’t Esposito say that all the windows were locked from the inside?” Dean said. “I’m no expert on New York apartments, but usually window locks mean no entry.” 

“Our killer’s a pro,” Beckett countered. “He knows how to reset interior locks.” 

“Except Will lives on the nineteenth floor. With no fire escape,” Castle pointed out. 

“Come on, Castle. You know that there are plenty of ways to access windows on high-level floors without a fire escape.” 

“Agreed.” Castle leaned in closer to her and lowered his voice to a still-audible whisper. “Because it’s _the devil_.” 

Sam bit back a smile. Watching Castle’s insistence on a supernatural culprit was amusing… and Sam new it was true. 

“The only place we’re going to find the devil in this case is in the details,” Beckett said with a dubious look. “Once we find out more about Will’s life, then we will uncover who his _earthbound_ enemy is.” 

“We’re going to go do some digging ourselves,” Sam said. He grabbed a notepad and a pen from Beckett’s desk and scrawled the address of their hotel and his cell phone number on it. “This is where we’re staying while we’re in town, and my cell number if you need to reach us.” 

“I’ll keep you updated, Agent,” Beckett said with a cordial nod. 

“Thank you, Detective Beckett,” Sam replied. “Good night. You too, Mr. Castle.” 

“Until tomorrow,” Castle called as Sam and Dean made their way toward the elevator. When he was sure they were more or less alone, Castle crept closer to Beckett. “Speaking of uncovering… should we head home?” 

Beckett smiled, though the moment was interrupted by the ring of her desk phone. 

“Don’t answer it, don’t answer it, don’tanswerit,” Castle begged. Beckett hesitated for a moment, then picked up the receiver. 

“Beckett,” she said. Her eyes darted over the floor as she listened to the caller on the other end. “Oh, sure Lanie, we’ll be right down.” 

“Lanie,” Castle hissed. That meant their trip home would be delayed, and that Beckett’s mind would be on the case instead of more pleasant matters. 

Beckett hung up the phone with an apologetic smile. “Come on, Lanie’s got something down in the morgue.”

 

* * *

 

“On closer examination of the body I found multiple stress fractures here, on the victim’s left wrist,” Lanie, the Precinct’s resident medical examiner, pointed to the area with her pen, a clipboard in her other hand. 

“From what?” Beckett asked. 

“They’re consistent with flexion, extension, and hyperextension, as a left-handed person would experience if they—” 

“Tried to defend themselves against something,” Beckett finished. “So Will was left-handed. Are you saying he smashed up his own apartment?” 

Lanie nodded, and Beckett looked back over the body of the victim. 

“I guess that rules out robbery.” 

“But not hellhounds,” Castle noted, earning an unamused glance from Beckett.


	4. Chapter 4

The next morning, Castle and Beckett arrived at the Precinct early. 

“I’m telling you, something about those guys doesn’t add up,” Beckett insisted. “I’ve worked with enough federal agents to know one when I see one. Those guys aren’t.” 

“I was thinking about that,” Castle said, taking his usual chair next to Beckett’s desk. “Have you ever seen a movie called _Fletch_?” 

Beckett shook her head. 

“Seriously? Chevy Chase, a paid assassination plot gone sideways because Fletch is suspicious about it? Car chases and romance and money?” 

“Explain it all you want, Castle, it won’t magically make me know it.” 

“Anyway, those names are from that movie,” Castle explained. “Mr. Stanwyk is the film’s bad guy, and Fletch, the main character, goes by a bunch of pseudonyms as he’s investigating something, including ‘Mr. Babar.’” 

“You think it’s worth checking out?” 

Castle hesitated. 

“Castle?” 

“They’re nice enough guys, but if they’re not who they say they are…” 

“We should know about it,” Beckett nodded. “Hey Espo!” 

Esposito, setting his stuff down at his desk, looked up at her. “Yeah, Beckett?” 

“Think you could call in a couple favors with some of your old contacts?” 

“Whaddya need?” 

“Run a check on those agents for me, would you?” 

Esposito took off his jacket. “You think they’re dirty?” 

“I don’t know about dirty,” Beckett said. “But something about them rubs me the wrong way.” 

“I’ll see what I can find out,” Esposito promised, heading for one of the workrooms off the Precinct’s bullpen. 

“So, Detective Beckett,” Castle said, an air of boyish mischief in his voice. “What would you do if you were attacked by an invisible demonic force?” 

“I’d tell Ryan to lay off the bean burritos at lunch,” she said with a cheeky smile. Castle chuckled as the elevator dinged and Ryan walked in. 

“Hey guys!” 

“Hey Ryan,” Beckett greeted, exchanging a private glance with Castle. 

“Looks like you were right: Will’s troubles may have followed him home from O’Neil’s pool hall. I spoke with several witnesses that said that he got into an altercation there last week with an ex-con named Jiggy Michaels.” Ryan clipped a photo to the murder board. A mugshot of a man, bald—probably by choice—with a short beard and moustache, shooting the camera an unamused look. 

“How serious was the altercation?” 

“Well, Jiggy smashed a beer bottle, threatened to kill him. Several people had to hold him back.” 

“I’d say that qualifies as serious,” Castle muttered. 

“It gets better,” Ryan continued. “Apparently Will hustled him out of twenty grand.” 

“Exactly the amount we found in Will’s apartment,” Beckett said. 

“Plus, Jiggy has over a dozen priors, including multiple B and E’s. He can get in and out of almost anywhere undetected. They call him ‘the ghost.’” 

“Wow,” Beckett said. “A real-world killer who could’ve broken into Will’s apartment without leaving a trace. Now _that_ makes perfect sense.”

 

* * *

 

Sam and Dean slipped into the observation room alongside Beckett and Castle as Ryan and Esposito interrogated Jiggy. 

“Hey,” Dean greeted. “What’d we miss?” 

“Suspect,” Beckett said, careful not to let too much information slip. She still wasn’t sure she could trust these men. 

“We’ve got a taxi receipt dropping you off in Chelsea last night, three blocks from Will’s apartment,” Esposito said, his voice sly, twisted. “That’s a long way from your place in Cypress Hills, Jiggy.” 

It was a voice Jiggy had heard before, but this time, he was clean. He sighed in annoyance. “My boyfriend lives in Chelsea. I was with him all night.” Dean and Castle happened to catch each other in shocked looks. “And Will didn’t hustle me, he _cheated_ me. After gaming, that Cujo bet me double or nothing, and then cleared the table with a single shot.” 

“What are you talking about?” Ryan asked. 

“It was… like that cue ball was… _possessed_ or something.” 

Dean narrowed his eyes slightly, while Sam looked over at an overexcited Castle trying hard to catch Beckett’s attention. Castle instead saw Dean’s knowing expression, and settled for observation—both of the interrogation and of the men beside him. 

“No one is that good or that lucky,” Jiggy continued inside the interrogation room, “so yeah, I got pissed. But I didn’t kill the guy. In fact, Will tracked me down the next day and offered to give the money back.” 

“What, out of the goodness of his heart?” Esposito asked. 

“No. He wanted to know something.” 

“That’s some expensive knowledge,” Ryan said. “What’d you do for him?” 

“He wanted me to case a brownstone on the Upper East Side.” 

Ryan scoffed. “Is that all?” 

“Hey, I don’t do that stuff anymore. Will just asked how he could break in himself.” 

“Why?” Esposito cut in. “What was so special about that brownstone?” 

“I don’t know, but it wasn’t going to be easy,” Jiggy said. “Place had the works: motion detectors, motion _and_ thermal sensors…” he shook his head. “You’d have to be nuts to try to go in there.” 

Ryan and Esposito looked at each other and nodded. 

“What do you say that we—forget—that you were acting like a Wikipedia of B and E’s…” Esposito began. 

“And you give us the address of that brownstone?” Ryan finished.

 

* * *

 

Beckett hung up her phone after confirming the address Jiggy had given them and the identity of the apartment’s owner. 

“There was a break-in at 39 East 70th Street earlier this week,” she said. “And the owner, Tom Talmadge, was assaulted.” 

“Tom Talmadge…” Castle furrowed his brow. “Talmadge, Talmadge, Tal—wait.” He whipped his phone from his pocket and typed something into it. “He invented that thing you put into your car, the one that calls it to you. He’s made millions!” He showed the image to the others circled around him. 

Sam nudged Dean. “Hey, what if we—” 

“No.” 

“But it could be—” 

“I don’t care how useful it could be, I’m not putting _any_ of that newfangled crap in _my_ car,” Dean snapped. “I still haven’t forgiven you for that time you douched her up with an iPod jack…” 

Beckett held back a laugh. 

“Why would Will want to break into a millionaire’s house?” Castle asked. 

“I don’t know, but here’s the weird thing: Tom was hospitalized. And he refused to give a description of the attacker.” 

“And Will showed up dead a few days later?” Sam said, raising an eyebrow. “That can’t be a coincidence.” 

“No,” Beckett agreed. “Talmadge is hiding something. We’re going to find out what.”

 

* * *

 

After Castle and Beckett had tried unsuccessfully to get a statement from Talmadge at his hospital room, they reluctantly allowed Sam and Dean to have a go. 

“Look, I told the other cops and now I’m tellin’ you: I don’t care who you are, I’m _not_ giving a statement!” Talmadge insisted. 

“We’re not going to ask you the same kinds of questions,” Sam said. 

“Did you smell any sulfur?” Dean asked. 

“Sulfur?” Talmadge repeated. “Like rotten eggs? None of that, no. What kind of cops are you guys?” 

“Not cops.” Dean showed Talmadge his badge. “We need information on Will Fairwick, and anyone he might have been connected to.” 

Talmadge’s expression turned serious. “Look, I’m sorry he died. He was a good guy, but—” 

“So you knew him?” Dean asked as Sam pulled a chair over to Talmadge’s bedside. 

Talmadge looked as though he realized he’d said too much, his lips thinning into a straight line. “You guys are gonna think I’m nuts.” 

“We’ve heard crazy before, Mr. Talmadge,” Sam said. “And if you don’t mind me saying so, you don’t seem crazy to me.” 

Talmadge sighed. “I heard barking. I figured one of the neighbor’s dogs had gotten out again, so I opened the door to check it out. When I didn’t see anything, I went back inside, figuring I’d just heard someone’s TV or something. No harm done.” Dean nodded. “But then, something knocked me over.” 

“Something?” Sam repeated. 

“Yeah,” Talmadge said. “It was right on top of me, suffocating me, but I couldn’t see what it was. It was… invisible.” 

“Do you know what this… _thing_ wanted?” Dean asked. “Was it trying to kill you?” 

“Maybe, I don’t know,” Talmadge said, the blip on his heart rate monitor increasing slightly. “I can’t imagine why it would…” he shook his head and looked from Dean to Sam. “I’m sorry, I can’t tell you anything else.” 

“You didn’t see anyone or anything?” Dean said. 

“No. I’m sorry.” 

“That’s okay, Mr. Talmadge. Thank you for your time,” Sam said politely as he ushered Dean from the room, closing the door gently behind him. 

“Anything?” Beckett asked, eyes dejected. 

Sam hesitated. “Maybe, but I don’t know if we’re any closer to a lead on your killer.” 

He and Dean relayed Talmadge’s story to Beckett and a very enthused Castle, who was enthralled about the idea of a supernatural element in a case. 

“We’re not dealing with hellhounds, Castle,” she sighed. 

“But it would be so _cool!_ ” Castle insisted. “Think about it! Demonic doggies from the depths of hell itself. Could we keep it if we find it? Please?” 

“If it _was_ a hellhound, it’d be our killer,” Beckett said. “You really want a pet with a taste for human flesh?” 

Castle’s gleeful expression quickly faded as Beckett’s phone rang. 

“Beckett,” she answered. 

“Beckett, it’s Esposito,” came the reply. “Get back over here. I got some info on your FBI boys that you might want to know about.” 

Beckett kept her expression carefully neutral. “Got it. Thanks, Espo.” She stashed her phone in her pocket. “Espo might have something for us. Let’s go.”


	5. Chapter 5

Sam and Dean looked over the murder board and Castle and Ryan were discussing something close by. Across the room, Esposito and Beckett spoke in hushed voices. 

“I ran their names through every database I could find,” Esposito said. “Nothing popped.” 

“Who are these guys?” Beckett asked, a hand on her chin. 

“Facial recognition puts them at an 82% match with a couple of actors from Texas, but I checked on their whereabouts: they’re filming some TV show in Canada.” 

“It’s not a long trip from Canada to New York,” Beckett said. 

“Wouldn’t explain why they’d be here though,” Esposito countered. “Besides, I’ve seen actors. These guys aren’t soft enough to be actors.” 

“Maybe, but they’re not FBI.” Beckett’s appearance was calm, but alarm bells were ringing inside her head. With a nod, she motioned to Esposito that he could leave, and she stepped closer to Sam and Dean. She slid her gun from her desk and held it at her side, her arm tense. 

Castle’s eyes had been trained on her the whole time. “Beckett, what are you doing?” 

Sam was the first to spot Beckett’s piece. “Dean!” 

Dean drew his gun, aiming it for Beckett’s chest, as he threw Sam behind him. Beckett reflexively brought her gun up to aim it at Dean, her stance confident. 

“What’s going on?” Dean asked. 

“Beckett?” Ryan asked cautiously. 

“Espo ran your names,” Beckett said. “No ‘Agent Stanwyk’ or ‘Agent Babar’ in the FBI. Or _anywhere_.” She narrowed her eyes. “Who the hell are you, and what do you want with my case?” 

“We want to catch your killer, same as you,” Dean said in as calm a voice as he could muster. 

“I don’t buy that for a second,” Beckett hissed. She cocked her gun. 

“Whoa, whoa!” Castle rushed to her side. “No need to go _that_ far!” 

“Right now, they’re a danger to us and to everyone in this station,” Beckett said through gritted teeth. “And if they don’t tell me the truth about why they’re here, you can be damn sure I’ll shoot.” 

“Over my dead—” 

“Hey,” Sam cut his brother off, placing a hand on top of his arm. “Let me?” 

Dean didn’t protest, but also didn’t lower his weapon. Sam stepped in front of Dean, his hands raised. 

“My name is Sam Winchester,” he said. “This is my brother, Dean. We’re… hunters.” 

“Yeah?” Beckett snorted. “Nice camo.” She hadn’t moved, either. 

“We don’t hunt deer or whatever,” Sam continued. “We hunt monsters. Ghosts and vampires and werewolves. Everything that goes bump in the night. We kill it.” 

Castle’s face was frozen in an expression somewhere between shock and glee. 

Beckett broke the silence. “Bullshit.” 

“But that’s so _awesome!_ ” Castle exclaimed. 

For the first time since she’d drawn her gun, Beckett broke her line of sight. “You’re saying you believe this guy?” 

“I want to believe,” Castle said. 

“It…” Sam sighed. “It doesn’t exist in your New York. Usually. Where we come from, it’s all over.” 

Beckett’s glare shot back to Sam. “What do you mean, ‘our’ New York?” 

“It’s sort of a parallel universe thing. We’re here from ours because something got into yours.” 

The grin on Castle’s face was spreading, while Beckett’s disbelief was deepening. 

“Don’t believe me?” Sam said. He pulled out his phone and dialed Crowley’s number, one of the few he was sure would work in this world. The King of Hell answered with video. 

“Hello, Moose.” 

“Crowley, we’re in a bit of a situation,” Sam said. 

“Who the hell is that?” Beckett asked. 

Sam hesitated. “Um… the King of Hell.” 

Beckett shot him a doubtful expression and grabbed his phone from him. “This is Detective Kate Beckett, NYPD. I have your cronies at my station.” 

“The Winchesters aren’t my cronies,” Crowley growled. “I’d rather I didn’t have to associate with them, but I found myself in a rather uncomfortable situation.” 

“Right,” Beckett sighed. “Let’s hear it.” 

“One of my hellhounds escaped,” Crowley said. “Sent them to bring her back.” 

“Her?” 

“Hellhound?!” Castle exclaimed. 

Crowley’s face twisted. “Who was that?” 

Beckett rolled her eyes as Castle crammed into the screen beside her. “That’s Castle, my partner.” 

“Nice to meet you, Your Majesty,” Castle said. 

“Huh,” Crowley said, surveying Castle. “Nope. Liked you better in brown.” 

Beckett looked Castle up and down while the latter raised an eyebrow in confusion. 

“Anyway, the Winchesters have caused a lot of trouble for my demons. They’re the real deal.” 

“Demons?” Beckett said. 

Crowley’s eyes turned blood red. “No filter.” 

The color drained from Beckett’s face, and Castle squeaked like a rusty wheel. 

“Easy, Captain Mal,” Crowley said, his eyes reverting to normal. “What would you do if I told you this was just a meat suit?” 

“Meat… suit?” 

“Better than your sport coat.” 

“Sir…” a voice from Crowley’s end of the phone said. “We need your input on a situation.” 

Crowley rolled his eyes. “Hell,” he sighed. “It’s a nightmare. Gotta go—I’ll call you if I need anything smuggled. Say hi to Squirrel for me.” 

“That punch freakin’ _hurt_ , you douchebag!” Dean yelled as Crowley disconnected. 

Beckett handed Sam’s phone back to him. Her hands were slightly shaky. 

“Now do you believe us?” 

Beckett put her gun down. “Let’s say, for a minute, that I do,” she said cautiously. “Why would a hellhound kill Will Fairwick?” 

“It’s possible that Will did make a deal with a crossroads demon,” Dean said, putting his own gun away. “If that was the case, then his time might have been… up.” 

“That wouldn’t explain the attack on Talmadge, though,” Ryan pointed out from slightly farther away than he had been before. 

“No,” Sam said. “But from what he told us, it sounds like it was the hellhound we’re looking for that attacked him.” 

“But it’s invisible,” Castle said. “How do we find it?” 

“We follow the clues, see where the investigation leads us,” Sam said. 

“And we use the glasses,” Dean added. 

Castle looked at him sideways. “Glasses?” 

Sam and Dean showed Castle and Beckett out to the Impala. They opened up the trunk, revealing their assortment of monster-killing implements. Castle’s eyes glowed with delight, as Beckett took stock of how many of those weapons were illegal in New York. 

“Will you look at all of this, Beckett?!” Castle exclaimed. 

“I’m looking,” Beckett said dryly. 

“A lot of what we do is off the record, Detective,” Dean said. He found a case tucked carefully away and opened it, pulling out a pair of glasses. 

“These are the glasses?” Beckett asked, taking the spectacles from Dean. 

“They’re not nearly as cool as half the other stuff in here,” Castle said. 

“Maybe not, but they were scorched in holy fire. That’s what lets us see hellhounds,” Sam explained as Beckett turned the glasses over in her hands. 

“They’re also far less illegal than most of this other stuff,” Beckett said, handing the glasses back to Dean. “So we have a way to see it—” 

“Her, actually,” Sam corrected. 

Beckett raised an eyebrow, but continued. “ _Her_ when we find her. But we don’t have any other leads.” 

“Yo, Beckett!” 

Everyone turned to see Esposito jogging out to them. 

“Yeah, Espo?” 

“You didn’t take the DVD with the security cam video from Will’s apartment this morning, did you?” 

“No. Why?” 

“I was going to look it over again, but when I went through the evidence locker, it wasn’t there.” 

“What?” 

“The DVD’s just gone,” Esposito shrugged. “That locker’s under constant guard, and the last person there was you.” 

“You’re sure you went through everything?” 

“Twice.” 

Beckett ran a hand through her brunette curls. “This day just gets better and better.” 

“I’m getting his phone records now,” Esposito said. “Try calling Will’s apartment complex, see if they can send us the files again.” 

Beckett was already heading back inside. “On it.”


	6. Chapter 6

Dean and Castle were having a discussion in the break room—one that was delighting Castle—as Sam and Beckett sat at her desk. Their conversation had wandered from the case to their university careers: they were comparing notes on how and why they’d left pre-law when Esposito interrupted them. 

“Hey,” Esposito said. “Anything?” 

“No,” Beckett grumbled. “I called Will’s place to pull security cam footage from the hallway again, and all the files have been erased. The doorman swears that no one has been in the security room since NYPD left the crime scene.” She took a sip of her coffee. “We got anything else on Fairwick?” 

“Ryan’s still trying to get in touch with his employer, Greenblatt Insurance, and Tory’s working on cracking his electronics. Apparently Will had some heavy encryption on his hardware.” 

“That seems a little excessive,” Sam commented. “Maybe I can help Tory. Where?” 

Esposito pointed toward a room off the bullpen. Sam nodded his thanks and left the desk. 

“Any good news?” Beckett asked, an air of defeat in her voice. 

“I just got his phone records from his wireless carrier. Dude didn’t talk much except to this number right here.” Esposito handed Beckett several papers with one highlighted phone number. “He traded dozens of calls with it over the last six weeks, and he didn’t ever call it before then.” 

“They talked almost every day,” Beckett said, scanning the pages. “Who owns this number?” 

“It’s registered to a Donna Brooks. Says here she’s an animal biology professor at Hudson U.” 

Beckett furrowed her brow. “Why was Will talking to an animal biology professor?”

 

* * *

 

Beckett, Castle, and Dean had gone to Donna Brooks’ office at Hudson. Castle had insisted that, given Dean’s knowledge of the supernatural, he might be an asset to their interview, though Beckett suspected he just wanted to hear more stories about Dean’s hunts. 

Beckett was the one to tell Donna of Will’s death after they arrived. She had always been the kindest when delivering that kind of news. 

“I haven’t heard from him in a few days. I…” Donna blotted away tears with a tissue, seated on the couch in her office. “I was worried, but I never imagined this. I can’t believe he’s dead.” 

“Donna, I know this is hard, but how do you know Will?” Beckett asked, her voice soft and comforting. 

“Um…” Donna sniffled. “I guess you could say we were dating. He reached out on Facebook a couple months ago. I hadn’t seen him since we first dated back at MIT.” 

“An anarchist pool shark attended MIT?” Castle asked. 

Donna nodded, a sad smile tugging at one corner of her mouth. “He was always a rebel. And the smartest student in our class.” 

“Why did he get back in touch?” Dean asked. 

“Will dropped out after only a semester,” Donna explained. “He said he wanted to talk about finishing his degree, enrolling here at Hudson. It was crazy. Even after all that time, the spark was still there between us.” 

Castle had been looking at photos on a bookcase against one of the walls of Donna’s office. One of them—a relatively old photo, judging by the year on the frame—was of Donna clothed in graduation robes, snuggling a black cat. 

“One of my senior pictures,” Donna said. “That was my cat, Salem. He was part of the reason I went into biology. He died just before I finished high school.” 

Embarrassed that he’d been caught, Castle quickly put the frame down. “Cute,” he said sheepishly. 

“Donna, did Will ever mention the name Tom Talmadge?” Beckett asked. 

“Um… no, not that I remember.” 

“And was there anything out of the ordinary going on in Will’s life?” 

“Like way, _way_ out of the ordinary,” Dean added. 

“Now that you mention it, yeah,” Donna nodded. “Will started acting paranoid last week. We went to dinner and he would only take a table facing the door. He said he thought he was being watched.” 

“By who?” Beckett asked. 

“He would only say ‘by them.’ I thought he was imagining it. I told him he needed to get help so it didn’t become MIT all over again.” 

“What happened at MIT?” 

“Freshman year, Will had a breakdown. He cracked under the pressure. That’s why he left. If somebody killed him then maybe he really was being followed.” 

As Beckett, Castle, and Dean left, Beckett noticed Dean staring at something. On their way out of the building, she poked him for more information. 

“Did you notice anything weird about her office?” Dean asked. 

“No. Did you?” 

“Her doormat.” 

“So she had a doormat. Lots of people do.” 

“Not my point.” Dean pulled his phone from his pocket and did an image search. “See this?” He showed the phone to Beckett and Castle. “This is what we call a devil’s trap. Those weren’t just symbols on that mat: they’re meant to keep demons out.” 

“Will was into that demon-y, anarchy stuff,” Castle noted. “Maybe it was from him?” 

“Or maybe she knows more than she’s letting on,” Beckett said. “Thanks, Dean. We’ll keep that in mind.” She checked the time. “It’s getting late. How about we get some rest and get started again tomorrow?” 

“Sounds good to me,” Castle said. 

“Come on, I’ll take you back to your brother.” Beckett motioned for Dean to join her in her car. 

“I call shotgun!” Dean called. 

“Hey, but I’m always shotgun!” Castle whined, running to catch up. “Beckett!” 

Beckett shrugged. “He called it, Castle.” 

Castle stomped a foot. “Dammit!”

 

* * *

 

At the Precinct the next morning, Sam, Dean, Beckett, and Castle were gathered around the murder board. Beckett was pacing and tapping a pen against her hand, trying to link clues together. 

“Donna might not be entirely trustworthy,” she began. “But what if Will _was_ having a psychotic break? He’d been talking about how his ‘time was up’ before he was killed: I’ve seen guys on PCP do much worse.” 

“But that doesn’t explain the attack on Talmadge or the security cam footage going missing,” Castle noted. “And let’s not forget: it looks like he _was_ attacked by a hellhound.” 

“But his time might not have been up,” Dean said. “Standard deals are ten years. I can’t see any old crossroads demon going for less than that if the guy just wanted to be a pool legend. He might have been crazy to waste a deal on that, but I don’t think he was psychotic.” 

“Dean might have a point,” Ryan said, rounding the bend from a hallway. “I finally got in touch with Greenblatt Insurance. They say Will’s on the payroll, but as a remote employee. Greenblatt’s only office is in Chicago and he’s never been there.” 

“Didn’t his neighbor say he saw him going to work every day?” Castle asked. 

“Yep,” Ryan nodded, “and his Greenblatt keycard was with his house keys, all scratched up and worn.” 

“So if Greenblatt doesn’t have a New York office, where was Will going every day?” Sam asked. 

“Sounds like Greenblatt Insurance is a front,” Beckett said, a hint of confidence slipping into her voice. “Ryan, where’s Will’s keycard now?” 

“Will’s apartment,” Ryan said. 

“If we’re going to Will’s apartment, we might want to bring the glasses,” Sam said. 

“Hang on,” Beckett said. “We can’t _all_ go to Will’s apartment.” 

“And why not?” Castle said. 

“Ever hear the phrase ‘too many cooks spoil the broth’?” 

Castle pouted over crossed arms. “You just don’t want me there.” 

“That’s not what I said,” Beckett defended. “What if the hellhound comes back?” 

Castle’s pout dropped into an expression of fear. “You know what? You’re right. You guys go. I think I’ll go help Ryan with… uh… stuff.” 

“But I don’t—” Ryan began. 

“Just keep walking,” Castle urged as he ushered Ryan away from the murder board. 

Beckett was grinning as she turned back to Sam and Dean. “So, roshambo?” 

“Not this time,” Dean said. “I got the sobbing professor, you get the dead guy’s apartment.” Dean clapped his brother on the back. “Have fun, Sammy.” 

Sam snorted. “You too, Dean.” 

Beckett checked her gun and grabbed her jacket. “So, Winchester, you got a piece?” 

Sam produced a gun from his pocket. “I’m all set.” 

Beckett nodded. “Then let’s go.”

 

* * *

 

Sam and Beckett ducked under the crime scene tape blocking off Will’s apartment. Sam surveyed the skulls, sigils, and drawings decorating the floors and walls. 

“Wow,” he said as Beckett turned on an end table light. “You guys really weren’t joking when you said Will was really into this stuff, huh?” 

“Yeah.” Beckett scanned the apartment. “Okay, keycard time.” 

Sam slipped on the hellhound glasses and they both began to search the apartment, checking in drawers and searching through piles of stuff. 

“Beckett,” Sam whispered from over by a desk. 

“Did you find it?” 

“No, but I think I found something else. Check this out.” 

Beckett crouched next to Sam, who was holding a small box. She picked at its contents: some dirt, a photograph of Donna, and a small bone. 

“Is this… some kind of shrine?” she asked. 

“No,” Sam said. “This looks like a crossroads box.” 

Beckett looked at Sam. “Like, to make a deal with a demon?” 

“Exactly.” 

“I know Will was into that stuff, but would he really have gone that far?” 

“Not Will.” Sam nodded at the photo. “To summon a crossroads demon, you need graveyard dirt, the bone of a black cat, and a photo of the person making the deal.” 

Beckett’s eyes shot back to the photo. “So… this was Donna’s box?” 

“Looks like it.” 

“But why—” 

Beckett was cut off by a low growl from behind her. She turned, but saw nothing. 

“Sam?” she gulped. 

Through his glasses, Sam could see the shadowy outline of a hellhound, easily half as tall as Beckett. Its burning red eyes were boring into her. 

“Hellhound,” he breathed. 

“What do we do?” 

Sam ripped a sculpture from the wall and tossed it at the hellhound’s legs. “Run!” 

Beckett darted to the side, and Sam ran for the kitchen, searching the cupboards for salt. Beckett screamed from somewhere else in the apartment, and he heard the sound of clothes tearing and rapid footfalls as she fled the hellhound’s razor-sharp claws. Finally, Sam located a familiar cylindrical canister. 

“Beckett?” he called. 

“Living room!” 

Sam grabbed the biggest knife he could find and made his way back to the living room. Ophelia was limping toward Beckett, who was standing on top of Will’s pool table. Her right pant leg was shredded, the remaining fabric stained with blood. 

“Catch!” Sam tossed the container of salt to Beckett, who looked at it, befuddled. 

“What the hell am I supposed to do with salt?” 

“It hurts them,” Sam yelled back. “Get ready to pour.” 

Ophelia was circling the pool table as Beckett opened the spout and held the container sideways with a shaky hand. Sam watched, waiting until Ophelia was perfectly positioned. 

“Now!” 

Beckett turned the container upside-down, sending salt cascading over the hellhound, who whimpered and retreated toward Sam. He slashed at her with the knife, slicing a deep gash into the front of her chest. Sam fumbled for the whistle Crowley had given him, but Ophelia was retreating through the door of the apartment, leaving a rather visible trail of blood on her way out. 

Beckett sighed with relief, her head falling back. “Thanks for that.” 

“Just don’t take me in for animal abuse. Toss me the salt?” Beckett complied, then slid down to the edge of the pool table, fashioning what remained of her pant leg into a makeshift tourniquet. Sam spread a thick line of salt in front of the doorway. 

“There,” he said, setting the container down. “That should hold her off, at least until we find that keycard.” He turned to Beckett. “How’re you holding up?” 

“Let’s just find that card,” she grumbled, limping toward a coat rack near the kitchen. Sam flipped on the lights, and in a couple of minutes, they’d located Will’s Greenblatt Insurance ID card. Beckett slipped the lanyard around her neck and they headed back toward her cruiser. 

“You need to get that looked at,” Sam said, supporting Beckett as she walked. 

“Lanie’ll take care of it when we get back to the Precinct,” Beckett winced. “Think it’ll scar?” 

Sam reached for the passenger door of Beckett’s car. “Probably not, if your M.E. is worth her salt.” 

Beckett rolled her eyes over a mildly-amused grin. “That was terrible.” 

“I know.” Sam climbed into the driver’s side and adjusted the seat. 

“Can you make it work, Jolly Green?” 

“Hey, I’m offended,” Sam said, turning the key. “I might be jolly, but I am definitely _not_ green.” 

“Actually, you handled yourself pretty well back there,” Beckett said. “I know I gave you and your brother trouble before, and I still don’t trust you, but you did just pull my ass out of the fire.” 

“Maybe literally.” 

“Yeah, I’d rather not think about that.” 

Sam nodded, a knowing grin spreading over his face. “That’s fair.” 

“You guys do this all the time?” 

“I’m sure you get asked that, too. It’s just an everyday thing for us.” 

Beckett nodded. She understood, maybe even sympathized. Putting her life on the line so others didn’t have to. Keeping watch. 

“And what about the fake FBI thing, _Agent Babar?_ ” 

Sam laughed. “Only when we need to.” 

“There are better ways, you know.” 

“Because you’ve never stretched the truth while you were working a case?” 

“I never did anything _that_ illegal.” 

“Ri-ight,” Sam said, his smile saying more than his words. Beckett shook her head, sporting a grin of her own as they drove back to the Precinct.

**Notes for the Chapter:**

> Yes, I added in Donna's cat. Yes, his name is a reference to _Sabrina the Teenage Witch_. NO I am NOT ashamed: Salem was _awesome!_


	7. Chapter 7

**Notes for the Chapter:**

> Fear the intimidating presence that is [Captain Victoria Gates](http://castle.wikia.com/wiki/Victoria_Gates). Seriously.

Back at the Twelfth, Captain Victoria Gates, who ran the precinct, corralled Beckett and Sam into her office the moment they stepped out of the elevator. 

“You were attacked at a closed crime scene? By whom?” 

“We didn’t get a good look at the assailant, Sir,” Beckett said, shifting her weight to keep it off her injured leg. 

“Do you know what this person was doing there?” 

Sam and Beckett exchanged a look. Neither wanted Gates to know they hadn’t been attacked by a human. “We believe they were after the victim’s keycard,” Beckett said. 

“Why? Were they trying to gain access to some part of Will’s life?” 

“If I may, Captain,” Sam said politely. “It’s possible that someone didn’t want us to find out what that keycard leads to.” 

“I’ve got CSU reprocessing the crime scene,” Beckett said. “They’re looking for new prints and Tory’s going to try to match the keycard to…” she winced. “… security systems, first thing in the morning.” 

“All right,” Gates nodded. “Keep me posted.” 

“Yes, Sir.” Beckett’s eyes lingered on the Captain’s a moment longer than they usually would have as she and Sam turned to leave. 

“Is there something you’re not telling me?” Gates asked. 

Beckett looked over her shoulder. “No, Sir.” 

Gates narrowed her eyes slightly. “Alright, Beckett. And if I may say: I approve of you taking Agent Babar to the crime scene instead of your…” she glared out toward where Castle and Dean were joking around. “ _Usual_ company.” 

“He and his partner have been a real asset to our investigation, Sir,” Beckett said, limping from Captain Gates’ office. Dean and Castle joined up with them on their way down to Lanie’s domain, and Sam and Beckett filled them in on their visit to Will’s apartment. 

“Detective Beckett, lying to your superior?” Castle said with mock surprise. 

Beckett rolled her eyes. “It wasn’t _really_ a lie,” she said. “ _I_ didn’t see what attacked us.” 

“Omission is the invisible lie,” Castle whispered as they approached Lanie’s door. 

“Are you going to be okay?” Sam asked. 

“Yeah, I think we got it from here,” Beckett said. “How about you guys take the rest of the night, and we’ll catch up tomorrow.” 

“Sounds good to me,” Dean said. “Maybe we’ll grab a drink at that bar you were telling me about.” 

“Tell Charlie I said your drinks are on me,” Castle called after him. 

Beckett hobbled into Lanie’s exam room as she was coming out of her office. 

“Kate!” she exclaimed. “What happened to you?” 

“She was attacked by a hellhound,” Castle said, helping Beckett into a chair. 

“Mmhmm,” Lanie said in her classic sassy tone. “What _really_ happened?” 

Beckett hesitated. “I was… attacked by a hellhound.” 

Lanie almost dropped the bandage she had retrieved as she looked between an overjoyed Castle and a slightly embarrassed Beckett. 

“Shut the front door!” she exclaimed. “Tell me everything.” 

As Lanie cleaned and wrapped the wound, Beckett again relayed the story of her excursion to Will Fairwick’s apartment. 

“Tell me you at least got the keycard?” Lanie said, securing the bandage with medical tape. 

Beckett held up the keycard. “After what happened with that security cam footage, I’m not letting this out of my sight.” 

“This is all way above my paygrade.” Lanie set her supplies down on the table next to her. “From what I can tell, your hellhound didn’t do any damage to the muscle or bone, but that is going to sting for a few days. As it is, I’m declaring you officially off-duty for the rest of the night.” 

“But Lanie—” 

“No buts, Kate,” Lanie said, donning the expression that could quiet her best friend with a glance. “That needs time to heal, and if I know you, you’ll be running around chasing criminals or… satanic dogs, apparently. Take it easy. Go home, have some dinner, watch a bad movie. Trust me, this case will still be here in the morning.” 

Beckett ran her thumb over the keycard. “Hopefully.” 

Lanie gave Beckett’s shoulder a squeeze. “I’ll see you tomorrow.” 

“Thanks, Lanie.” 

As they left the morgue, Castle spun around to face his fiancée. “I know you hate being told to take time off, but…” he took her hand. “I do know a way to take your mind off it for a while, if you’re… um… _interested_.” 

Beckett’s lips spread into a grin and she tightened her grip on Castle’s hand, pulling him toward the elevator.

 

* * *

 

Dean walked back to the table he and Sam had claimed in a corner of the Old Haunt, the bar owned by none other than Richard Castle. He placed a beer in front of Sam and sat down behind a towering hamburger and a full plate of french fries. 

“Courtesy of Rick Castle,” he said, taking a long, deep drink of his own beverage. 

“Thanks,” Sam said absentmindedly. 

“Come on, Sam, live a little!” Dean encouraged. 

“Sorry, I was just looking up Donna Brooks,” Sam said, turning his laptop around. “Get this: the newspaper in her hometown did a story on her MIT acceptance.” 

“Slow news week?” 

Sam chuckled. “Maybe. But it says here that her acceptance was unprecedented, that most people never get in as late as she did. They’re attributing it to school error, but after you saw that doormat at her office and Beckett and I found her crossroads box at Will’s apartment, I wonder if she made a deal to get in.” 

“You think she’s involved in Will’s murder?” Dean asked, popping a fry into his mouth. 

“I don’t know if she’s involved,” Sam said. “But I agree with what you said after you came back from that interview: she definitely knows more than she’s letting on.” 

“Who would tell the cops something like that, especially in a place like this?” Dean said. “Most people back in our neck of the woods don’t know about the supernatural, and according to Crowley, it barely exists here.” The corners of Sam’s mouth turned downward as he considered Dean’s point. 

“I mean, come on,” Dean continued. “We were committed for telling the truth, the whole truth, and nothing but the truth about Lucifer and the apocalypse, and that was in _our_ place. Here?” Dean took a drink. “I don’t even want to think about what they’d do here.”

 

* * *

 

The next morning, Tory gathered the team in her workroom. 

“The card’s RFID architecture is like nothing I’ve ever seen,” she said. “I can usually pull something, but…” 

“Is there anything you can tell us?” Sam asked. 

“Just that it’s not commercially manufactured.” Tory handed the card back to Beckett. 

“So how did Anarchy Boy get it, then?” Dean asked. 

“I don’t know,” Tory shrugged, “and it looks like there’s no way to find out. This card was designed to be untraceable.” 

Beckett ran the lanyard through her hands, stopping when she came across a tag. “Maybe the card was, but this wasn’t. ‘Proudly made in the USA by Advantus Apparel.’”

 

* * *

 

“Sorry you’ve been delegated to backup, guys,” Castle said as he walked by Beckett’s side, Sam and Dean following close behind them. 

“Sorry my ass, you’re practically prancing,” Beckett said. 

“So, Advantus Apparel said they shipped the Greenblatt order to an office somewhere on this floor, right?” Sam said, looking around the empty, sterile hallway. 

“Right,” Beckett confirmed. “Now we just have to figure out which one.” She tried the card on a lock pad, but to no avail. 

“What is this place?” Castle asked. 

“I don’t know,” Beckett said, turning around and heading for another lock pad. “This whole floor is unlisted.” 

“Maybe they’ve got an interdimensional portal here,” Castle said. “Or a pack of hellhounds.” 

Beckett looked at him skeptically. “You were right about the first hellhound. Do you really want to be right again?” 

Castle thought it over. “As much fun as having a satanic puppy would be, it might be difficult to take care of something we can’t see.” 

“You’re a poet and don’t know it,” Dean laughed. 

“Actually, I _do_ know it,” Castle said. “I won the—” 

“Whatever’s on this floor,” Beckett interrupted. “That hellhound went after Sam and me so we wouldn’t find it. With a little luck, we might get closer to our killer.” She swiped the card again. 

The door nearest the lock pad opened to reveal a large, blindingly white room. 

“Who wants to bet this isn’t Greenblatt Insurance?” Castle murmured. 

“We’ll stand watch out here,” Sam said. “Give us a shout if you need anything.” 

“Thanks,” Beckett said. She strode confidently through the doors, Castle following hesitantly. The doors closed smoothly behind them. 

“I don’t like this, Sam,” Dean said, his voice low. 

“You had to know Greenblatt Insurance was a cover.” 

“I mean this place,” Dean’s eyes darted around the hallway. “Something feels wrong.” 

Sam nodded. “Yeah.” 

“So,” Dean said. “You hung out with that Tory chick back at the Precinct, right? Think she’d let me take her out for drinks?” 

Sam held back a laugh. “I don’t think you’re her type, Dean.” 

“What, heroic and witty isn’t her type?” 

“Um… I think _male_ isn’t her type.” 

Dean looked slightly taken aback, then disappointed, and then impressed. “Think she’d let me watch?” 

Sam rolled his eyes. 

“Hands!” a voice commanded from inside the room. Sam and Dean whipped around, but despite their best efforts, couldn’t open the door. Turning around, they faced several armed guards of their own. 

“Hello, boys,” Dean said. “What brings you up here?” 

“Hands in the air,” one of them said, gesturing with his gun. 

Sam looked over at Dean, whose arm was tensing to reach for his own weapon. 

“Dean,” Sam said softly. Dean looked over at his brother. The look in Sam’s eyes was all he needed to see. 

Dean sighed and put his hands up. They were escorted into the room beyond the doors, where more officers surrounded Beckett and Castle. They looked over as Sam and Dean were seated—forcefully—in the chairs next to the others. 

“Hey,” Castle said weakly. 

“So much for being backup,” Dean sighed. 

A man walked through the throng of officers and approached Beckett. “Your credentials check out, Detective,” he said. “If you and your compatriots vacate the premises immediately, we’ll refrain from filing federal trespassing charges.” He returned her badge and gun to her. 

“I’m sorry, but we’re investigating a homicide,” Beckett said. “We’re not leaving without answers.” 

Castle raised his hand. “Uh, federal charges?” he asked. He looked over at Beckett. “What’s the government doing dabbling in the supernatural and hellhounds?” 

“What did you say?” the man barked, turning his attention from Beckett to Castle. 

“I—I—I was right,” Castle stammered. 

The man’s earpiece beeped, and he pressed on it, listening intently. Castle looked between him and Beckett, his eyes frightened. 

“Copy that, ma’am,” the man said with a nod. He walked over to a door and held it open, revealing a fair-skinned woman with wild, red hair. He glared one more time at Castle, then disappeared through the same door. 

“Hello,” the woman said, addressing all four of them. “I’m Elena Sarkov, the head of this facility. Mr. Castle, what was it you meant by ‘supernatural’?” 

“You were listening?” 

Sarkov continued to look at him with a calm expression, awaiting an answer. 

“I… I was just saying that—” 

“Castle,” Beckett snapped. She shot a sharp glare at Sarkov. “If you want answers, you’re going to have to give us some first.” She raised an eyebrow. “Unless you want the full force of the NYPD knocking down your front door.” 

Sarkov sighed deeply, her collected look cooling. “What do you want to know?” 

“What is this place? And how is Will Fairwick connected to it?” 

“Mr. Castle was right: this is a government facility.” 

Castle’s eyes lit up. “CIA? Homeland Security. Uh… DARPA.” 

“If you like,” Sarkov said with a knowing smirk. She turned back to Beckett. “Will worked here. His death was… quite a loss to us.” 

“So you know he was murdered,” Beckett said. 

“What did Will do here?” Dean asked. 

“He was one of my scientists. Maybe the most brilliant man on our team. I recruited him out of MIT.” 

“So he never had a breakdown?” 

Sarkov shook her head. “Cover story to avoid questions.” 

“But what was going on here that was so compelling to him?” Sam asked. “Why would Will leave MIT to do government research?” 

“Aside from the substantial benefits package?” Sarkov said. “Will was scared.” 

“Scared?” Castle said. “Scared of what?” 

“We all make our own deals with the devil, Mr. Castle,” Sarkov said. “Will’s was just more literal than most. The technology we work on here is aimed at control, prevention, protection. We’ve been working on a device that would let us control hellhounds, coding it to use a range of frequencies inaudible to humans, but that such creatures would react to.” 

“How do you even know about this stuff?” Sam asked. 

“There is more to this world than most believe,” Sarkov responded. “As much as other scientific minds would like to deny them, occult forces are very real. Will was working to prove that they can be manipulated.” 

“Sam,” Beckett said, whipping around to face him. “That would explain why the hellhound attacked us in Will’s apartment: someone was pulling the strings.” 

“Whoever killed Will might have been controlling Ophelia, too,” Dean added. “That’s why they didn’t want you getting that keycard, so you never found out.” 

“As much as I hate to interrupt your brainstorming session,” Sarkov cut in, “I’m afraid that isn’t possible.” 

“Oh?” Castle said. “And why’s that? Didn’t you just say that hellhounds were real? That they could be controlled?” 

Sarkov looked almost embarrassed. “It’s not possible because we haven’t gotten our technology to work. We’ve had only one test subject, and it ended… badly.” 

Sam and Dean winced. They knew precisely the ending Sarkov meant. 

“However…” Sarkov continued, leading the four further into the lab. “We recently suffered a crippling cyber-attack. All of our data was wiped out. Our team managed to trace the virus to a relay station in Shanghai.” Sarkov stopped at a screen displaying lines of code in Chinese. “This has led us to believe that an agent of the Chinese government is after our research.” 

Beckett scanned the screen. “What would the Chinese want with this kind of information?” 

“We’d heard that a secret research cell was pursuing similar technology. Think of what they could do with control of the supernatural,” Sarkov said. “They could command empires, win wars, make any demand they pleased. This is a good defense in the right hands, Detective, but a powerful weapon in the wrong ones.” 

Dean was lost in thought as he stared at their control device, a little handheld remote. It looked so inconspicuous. He wondered if things could have turned out differently when he’d been dragged to hell, all those years ago, if they’d had something like this. He wondered what he and Sam could do with something like it, how many people they could save… or kill. 

Sarkov stepped away, called over by another scientist, and Castle and Sam joined Beckett at the computer screen with the virus code. 

“I don’t think it was the Chinese,” Castle said. 

“I agree,” Sam nodded. “They wouldn’t know to stop us from taking Will’s keycard.” 

“And they wouldn’t know about Talmadge,” Castle added. 

Beckett looked between them. “You guys are starting to weird me out a little. But you have a point.” 

“And then there’s this.” Sam pointed to one of the symbols on the screen. “That symbol repeats over and over in the virus, but it isn’t Chinese. I don’t know what language it—” 

“It’s not a language,” Castle interrupted. “It’s the symbol of the East Mountain Goblins. From Terra Quest.” 

“The online game?” Beckett asked. 

“Exactly. And who do we know that’s a master of Terra Quest?” 

Beckett’s eyes widened. “But… it couldn’t be—?” 

“One way to find out.”


	8. Chapter 8

Dean clipped a photo of Henry Wright, Will’s neighbor, to their murder board. 

“Unis went to Henry Wright’s apartment and found it cleaned out,” Esposito reported. “Closet, dresser, empty. Dude’s gone.” 

“What have we found on him?” Beckett asked, eyeing the photo on the whiteboard. 

Esposito opened a file folder. “He’s a serious hacker. At fifteen, he cracked the city’s power grid. He didn’t get scared straight until he was in his 20s. Now he’s a sneaker, testing cyber defenses for Fortune 500 companies.” 

“Which means he had the skills necessary to launch a cyber-attack against Sarkov’s lab,” Beckett concluded. 

Ryan turned around in his desk chair, moving aside to show his computer screen. “And he had another connection to this case. Henry attended Cal Tech with—wait for it—assault victim Tom Talmadge. They were roommates. And this is the lawsuit that Henry filed against Talmadge, accusing him of stealing the code that he used to build his car-calling app. The court dismissed the case.” 

“Which would have cost Henry millions,” Castle said. 

Sam looked thoughtful. “Sarkov said her lab hadn’t cracked the technology to controlling the hellhounds, but what if Will did?” 

“With a little help from his neighbor, Henry,” Dean added. “If they got it working, they could have easily gotten into Talmadge’s place for a little revenge.” 

“Not ‘easily,’” Ryan said. “Hellhounds might be invisible—” 

“And ridiculously strong,” Castle added. 

“But that doesn’t beat thermal or pressure systems. And how close would they have to be to control it?” 

“That’s where Jiggy must’ve come into it,” Esposito said. “That’s why they needed him to case the place.” 

“And what about the ‘possessed cue ball’?” Beckett asked. 

“Didn’t Elena say Will’s ‘deal with the devil’ was literal?” Sam interjected. “Maybe he made a deal to get really good at hustling pool. We’ve certainly heard of worse.” 

“And it would explain how they _got_ the hellhound in the first place,” Castle said with a nod. “It came for Will when his time was up.” 

Dean looked back at the murder board. “I don’t think so. I mentioned before that most deals give ten years before the hounds come to collect, right?” Dean turned to see a collective nod from everyone gathered in the bullpen. “Unless he also wished to age gracefully in his remaining years, I’m pretty sure the guy in this picture _isn’t_ 28.” 

Beckett stepped closer to the photo. “You… have a point,” she conceded. “But Henry’s not off the hook yet.” She spun around to face everyone else. “How do we find this guy?” 

“We don’t,” Esposito said. “The guy’s a high level hacker. By now he’s got a new ID and he’s out of the country. He’ll trade on his skills and live like a king.” 

At Esposito’s words, a look of realization spread over Castle’s face. “He’s already living like a king—and that’s how we’re going to find him.” Confidently, he led the others into Tory’s workroom. As he logged onto one of the computers and opened the browser, he explained his plan. 

“Tory, I’m going to log in to Terra Quest. People as big and powerful in the gaming world as Henry won’t leave their characters idle for long: with any luck, he’ll be there somewhere.” 

The Terra Quest welcome screen bloomed across the computer. A sensual, feminine voice welcomed Castle to the game as he bent in front of the monitor, elated. 

“Okay, bringing up the map…” Castle said, tapping a few keys. “The East Mountain Goblin army is attacking at the base of Mount Orr. Which means their king will be leading them into battle…” He guided his avatar to the area and through the horde of other players. Suddenly, he jumped up in excitement, pointing to the screen. “There he is! That’s Henry!” 

“Can you get a lock on that avatar and see if you can trace the location where Henry logged in?” Beckett asked Tory. 

“I think so,” she replied, focusing on her own computer. 

“And I will join the battle,” Castle said, faking heroism. “Slow him d—ooh, where’d he get a falchion sword? That’s like plus 90 conquest points.” 

“Focus!” Dean called. “We’ve got a battle to fight!” 

Castle nodded. “Right.”

 

* * *

 

Tory traced the IP address of Henry’s login to an underground gaming den in Brooklyn. Castle and Beckett ventured there to collect him and bring him in for questioning. 

“You should have seen it!” Castle boasted upon returning to the Precinct. “It was epic! I had a sword and everything!” 

“Nice work,” Dean said, shaking Castle’s hand. Beckett rolled her eyes as she wrestled Henry to the interrogation room. She sat him down and closed the door behind her, knowing everyone else was gathering on the other side of the two-way mirror. 

“I didn’t murder Will, all right?” Henry insisted. “He was my friend.” 

“Then why did you run, Henry?” 

Henry looked as if he wanted to say something, but decided against it. Beckett chose to fill the silence instead. 

“Look, we know that you went after Tom Talmadge. You were behind a cyber-attack that brought down a government lab. And then you cleaned out your apartment and you disappeared.” 

“Because I was afraid they’d come after me next!” 

“They who?” 

“The people who killed Will! If they found out that I knew—” Henry stopped abruptly. 

“That you knew what?” Beckett waited a moment for Henry’s answer, which didn’t come. “You helped him, didn’t you? You helped Will build a device to control hellhounds.” 

“It sounds crazy, doesn’t it?” Henry sounded defeated. “Will came to me with an out-there idea. Said he wanted to build something to use if… if something ever happened, you know? Because he knew things. And I knew things. But there wasn’t anybody in his lab that had my programming skills. And since there was no way I was going to get security clearance, we worked on the down-low.” 

“And in exchange you got to use a hellhound to get revenge on Talmadge, right?” 

“That was never supposed to happen!” Henry insisted. “I was just looking for proof that Tom stole my idea for the app.” 

“His broken ribs say otherwise.” 

“I was in his apartment, but I couldn’t find what I needed. The hellhound was just there as a backup, in case Tom came home early. I just wanted to mess with him. But I snapped. Will saw what I was doing and stopped me.” 

“So you got angry with him and decided to kill him instead, right?” 

“No!” Henry squeaked. “We both realized that I had become…” he searched for a suitable metaphor. “Frodo. And this control device was the One Ring to rule them all. Will knew it was too much power for anyone to have, especially the government.” 

“So that was Will’s Oppenheimer moment. The device became the atomic bomb.” 

“It needed to be destroyed. Cast into the fires of Mordor. We sabotaged the lab so they couldn’t rebuild the tech, at least not right away. And without the quantum cellular equations Will derived, they may never be able to.” 

“How did he do that?” Beckett asked. 

“Studied the biology of canids,” Henry said. “Knew as much about them as anyone who might have studied them in school.” 

That was Beckett’s “a-ha” moment. A smile tugged at the corner of her mouth. “Thank you, Henry. Someone will be in in a bit to process you out.” 

“S-so I’m good?” he called as Beckett dashed out the door and back to her desk, where Sam and Dean were sharing the story of Donna’s miraculous MIT acceptance with Castle. 

“We think we know where Will got the hellhound,” Castle said. 

“And I know where he got his research,” Beckett said. “Will didn’t get back in touch with Donna because he wanted to rekindle the romance: he wanted her brains—metaphorically.” She shuffled through some papers, finally locating the ones she needed. “Look at Will’s phone records. For weeks there were phone calls going back and forth between the two of them, and then right after Will died, Donna stops calling. Almost like she knew he was dead.” 

“Hey guys, I called the university,” Ryan called from across the bullpen. “Guess who canceled their class the night Will was killed?” 

Sam, Dean, Beckett, and Castle exchanged looks. They had their killer. 

Dean slapped Beckett’s desk. “Well, what’re we sitting around here for? Let’s go.”

 

* * *

 

While Sam and Dean headed for Donna’s lab, Castle and Beckett entered her office. They had just begun to search it when Donna stormed in, furious. 

“What’s going on here? This is a private office.” 

“An office that belongs to the university,” Beckett shot back. “The dean gave us permission to search it as part of our investigation. No warrant necessary.” 

“Wait, you think _I_ had something to do with Will’s death?” 

“You missed class the night he was killed, Donna.” Beckett crossed her arms. “Where were you?” 

“At home. With a cold. I would never hurt Will, I loved him!” 

“But then he betrayed you,” Castle said, walking around Donna’s desk to confront her. “He needed your research on animal biology. Once he had that, why would he keep seeing you?” 

“That was the second time he left you, and you weren’t going to take it lying down,” Beckett added. 

“You think that’s what’s going on?” Donna tossed her hair over her shoulder. “Detective Beckett, Will _blackmailed_ me into working with him. He said that if I didn’t help with his hellhound controlling device, he’d tell everyone how I really got into MIT.” 

“The crossroads deal,” Castle piped up. 

Donna nodded. “I told him no one would believe it, but I gave him my research anyway. Because my time was almost up.” 

“What Sam and Dean said about the timelines!” Castle’s voice filled with realization. “You made your deal at the end of high school, and you sped through graduate school.” 

“If I could control the hellhound that came to collect, maybe I could enjoy my deal a little longer.” 

“So how’d he end up dead, Donna?” Beckett asked. “Got a little trigger happy with your device?” 

Donna laughed. “No. Will borrowed it so he and his friend could use it, but I heard him talking about turning it over to the government. Why would he do that? After everything we…” She took a breath. “I decided no. _I_ needed to be in control. Will wasn’t going to end my life, by exposing me or by turning our work over to someone who was just going to lock it away. So I took the device back.” She narrowed her eyes at Beckett. “He never saw it coming.” 

“Donna Brooks,” Beckett began. “You’re under arr—” 

Donna pulled a display containing several labeled animal bones to the ground, smashing it behind her as she ran out of the office and toward the lab. 

“Why do they always run?” Castle groaned. 

“Come on, help me move this,” Beckett strained, gripping part of the display case that didn’t have shattered glass protruding from it. “We’ve got to catch her.”

 

* * *

 

Sam had the whistle from Crowley around his neck and Ruby’s knife in his hand as he and Dean surveyed the lab. Dean, decked out in the hellhound glasses and brandishing their salt shotgun, was watching the door. 

“You ever miss your college days, Sammy?” he asked. 

“Sometimes,” Sam admitted. “I don’t think I’d ever have gotten away from hunting completely, though.” 

Dean looked back at him. “Really? Why’s that?” 

“Think of how many times we’ve been to universities on our hunts,” Sam said. “Even here, one of the professors made a deal with a crossroads demon. If I actually did get into law school—” 

“Yeah, that place would be crawling with demons,” Dean muttered good-naturedly. “And I’m just talking about the lawyers.” 

Sam chuckled. “Right.” 

The otherwise lighthearted moment was interrupted by a low growling from down the hall. Both brothers turned their attention toward the sound. 

“Dean?” 

Dean nodded and crept closer to the door, readying the shotgun in his hands. “Come here, puppy. No one’s gonna hurt you.” 

Something about the tone of Dean’s voice still unnerved Sam a little: it was just like before the Mark of Cain had turned Dean into a demon. He enjoyed the hunt a little too much for Sam’s liking. 

Then again, in this case, if the hellhound was going to try to do them in, he’d much rather one of them killed it first. 

Sam readied the knife. He couldn’t see Ophelia, but he wasn’t going to let a little thing like that stop him. 

From just in front of Ophelia, Donna came tearing down the hallway toward them, skidding to a stop just short of the door to the lab. 

“You,” she said, glaring at Dean. 

He flashed her a winning smile. “Hi again.” 

“I assume you’re here about this?” Donna held up an almost exact duplicate of the controller they had seen in Elena Sarkov’s lab. 

“Donna,” Sam began, lowering the knife. “I know you’re scared, but—” 

“Scared?” she interrupted. She turned a dial on the remote in her hand. “Hardly.” 

From behind her, Ophelia howled—almost as if she was in pain—before lunging toward Dean. Both brothers dove out of the way as Donna strode into the lab to maintain her control. She sent Ophelia after Sam next, knowing he couldn’t see her. Sam ran toward the other side of the room, pursued by the hellhound. As he ran past the door to the lab, he slammed it shut. 

“What are you thinking?” Donna shouted over the crash of shattered glassware and the thud of Sam pulling down bookcases to attempt to slow Ophelia down. “You can’t run now.” 

“You’re wrong,” Sam called back, slightly out of breath. 

“ _You_ can’t run,” Dean finished from much closer to Donna than she’d expected him to be, tossing Sam the glasses. 

Sam caught the classes in midair and put them on in a fluid motion. He spotted the hellhound uncomfortably close to him, ready to pounce. Thinking quickly, he ducked beneath her and made a gash in one of Ophelia’s legs, simultaneously slowing her down and creating a means of tracking her movements via the blood dripping from the wound. 

Meanwhile, Dean was attempting to wrestle the control device from Donna’s hands when a loud pounding came from the closed lab door. It was enough to startle Donna into dropping the remote, which Dean kicked away. 

“Sam?” Beckett’s muffled voice shouted from the other side of the door. “Dean?” 

“We’re a little busy right now,” Dean called back as Donna clawed at him. Suddenly free of the device’s influence, Ophelia set her sights on Donna, and charged at her. Donna, knowing exactly what was happening thanks to the gash in Ophelia’s leg, abandoned her battle with Dean and ran toward Sam. Dean opened the door to let Beckett and Castle in, and reached for the control device. 

“It’s over, Donna,” Beckett said, raising her gun. Dean recovered the remote and held it up, pressing a middle button and stopping Ophelia in her tracks. “You’re under arrest for the murder of William Fairwick.” She shifted her gaze to Sam. “Sam, you were pre-law: why don’t you do the honors?” 

Sam held Donna’s hands behind her back. “I’d be honored, Detective.” Holding back a grin, he recited Donna’s Miranda rights to her as he led her to Beckett, who secured her in handcuffs.


	9. Chapter 9

“So, that’s it?” Castle asked as they watched Donna led off by two officers in uniform. “We’re done?” He turned to Beckett, a suggestive look in his eye. “We can go home?” 

“Actually, there’s one thing we still need to do,” she said with an apologetic brush against his arm. “Sam, Dean, I appreciate your help on this case, but you two impersonated federal agents, and there’s a hellhound in Manhattan that needs to leave immediately. I’m going to escort all three of you out.” 

Castle shot her a look. “Okay, but how?” 

Sam held up the control device. “I think we have that covered.” 

 

* * *

 

At Sam and Dean’s hotel room, Dean held the control device—Ophelia’s leash—as Sam knocked on the connecting door three times. Beckett stood close behind them, and Castle hung back. After a few seconds, Crowley opened the door. 

“Hello, boys,” he said. “Quite the rabble you’ve brought with you.” 

“I insisted on seeing them back to…” Beckett squinted, trying to make out the location behind Crowley. “Wherever this is.” 

“Hell,” Crowley answered simply. “I’m sure you’ve been told to go there a few times.” 

“Is that a threat?” 

“Absolutely not.” Crowley spotted Ophelia and bent down to call her. “Ophie! What did they do to you, girl?” 

“She was being controlled,” Sam said. “She came after us more than once.” 

“Someone who made a deal with one of _your_ demons used her to kill,” Beckett continued. 

“I don’t send my hounds after people whose time isn’t up yet.” Crowley glanced up at Sam. “Like I told you: I needed to keep my reputation intact.” 

“Wait,” Castle said, finally gathering the nerve to venture forward. “You’re saying Will _did_ make a deal?” 

Crowley tapped his nose. “I swear by my pretty floral bonnet. Wanted to be legend at pool. Sealed it myself.” 

Sam and Dean swapped slightly-amused, slightly-bewildered looks at the thought, while Castle could barely contain his excitement. 

“I knew it!” he exclaimed, pumping a fist. “I _knew_ he—” Castle met Beckett’s disapproving stare and immediately calmed himself. “I was right,” he said quietly, folding his hands in front of him. 

“They were using this to control your dog,” Dean said, moving to hand the control device to Crowley. 

Beckett cut him off, swiping the device from his hand. “ _Which_ I think we can all agree is far too dangerous for anyone to have.” She dropped the remote on the ground and crushed it beneath her heel, earning a wince from everyone in the room. 

“Thank you for that, Detective Beckett,” Crowley grumbled. Sam handed Crowley’s whistle back to him, which seemed to placate him slightly. 

“Now, if our business is done here—” Beckett began. 

“Not so fast,” Crowley interrupted. “You came to see the Winchesters off, didn’t you?” He looked between them. “Sorry boys: you know what comes next.” 

“No punching this time,” Dean muttered. 

Crowley sighed. “Fine, fine.” He touched two fingers to both of their heads and they collapsed on the floor. He nudged Dean aside with his shoe and stepped closer to Beckett. “As for you two…” 

With a snap of Crowley’s fingers, they were back at the Precinct. Castle looked at Crowley in awe, while Beckett looked around, scanning for any sign that it might be a trick or trap. 

“I can’t have you all remembering this,” Crowley said. “We keep tight control on the supernatural here. That your government is investigating it is concerning enough.” 

“And how are you going to—” 

Castle didn’t have time to finish. “There’s a trick to it.” With a flash, he was gone. The entire Precinct felt the jolt of his departure: their memories of Will Fairwick’s case had been rewritten. 

Crowley arrived back at the hotel room, Sam and Dean still unconscious at his feet. He shook his head. “Always messes to clean up.” He began to drag them through the door, not-so-accidentally knocking Dean’s head against the frame as he did.

 

* * *

 

Back at their Manhattan high-rise that night, Castle lit candles as Beckett settled into the couch. 

“Do you feel… weird?” she said, turning to him as he brought her a glass of wine. 

“What, without my mother and Alexis here? No, this feels just right.” He leaned in to kiss her. 

Beckett laughed and gave him a peck on the cheek instead. “No, I mean like someone screwed with your head.” 

“I’ve felt like that ever since I got back,” Castle said. “You’re feeling it, too?” 

“The Fairwick case today,” Beckett said, swirling the wine in her glass. “I was doing the paperwork for it, and I just felt like I was writing down details that I didn’t really remember.” Castle looked at her with concern. “I know we’ve got the killer. Everything adds up. I remember arresting her. But it’s like there’s something… missing.” 

“Maybe you’re just tired,” Castle suggested. “You know how you get when you’re working on a case.” 

“Yeah, you’re probably right. It just bothers me.” 

“Tell you what: we’ll go talk to Lanie tomorrow. Until then, I know something else you can think about.” 

Beckett leaned closer to him, a naughty smile spreading across her face. “Really?” She raised an eyebrow. “And what might that be?”

 

* * *

 

A throbbing pain pulsed in Dean’s head when he awoke in his bed, back in the Men of Letters bunker in Lebanon, Kansas. As far as he could tell, he was back where he should be. On a whim, he checked his arm: the Mark of Cain, the ancient biblical curse he’d obtained from Cain himself, was still burned into his flesh. 

Dean shook his head and pushed his sleeve back over his arm. He wasn’t going to let that thing control him. He had to try, for— 

“Sammy?” 

Dean checked his phone. No missed calls. Crowley might have a grudge against them, but he wouldn’t dare separate them… would he? 

Sam probably just hadn’t woken up yet. 

Dean cautiously left his room and headed toward Sam’s. As far as he was concerned, this wasn’t over until he laid eyes on his brother.

 

* * *

 

When Sam’s eyes fluttered open, he was at his desk in his bedroom. Almost everything seemed just like it was when Crowley had zapped them into parallel-universe New York… with two exceptions. Around Sam’s neck, cool against his skin, was the hellhound whistle Crowley had given him. In front of him was a note: 

 

_Don’t say daddy never gets you new toys._

 

Sam chuckled and pulled the cord over his head, turning the whistle over in his hands. He’d have to study this, figure out how and why it worked. It had to be better than whatever control device Beckett had crushed to pieces before they left. 

He sat back in his chair, tapping the whistle against his leg. He wondered whether they would ever encounter one another again. Sam was sure it was unlikely, but maybe, if they were ever in New York again, he’d— 

“Sammy?” 

Sam looked up to see Dean at his door. 

“Hey,” Sam said. “Looks like we’re back.” 

“Guess Crowley kept his word after all.” Dean sat at the foot of Sam’s bed. “Never would’ve figured.” He nodded at the whistle in Sam’s hand. “What’s that?” 

“A parting gift.” Sam held the whistle up for Dean to see. “From Crowley.” 

“What’s it do?” 

Sam grinned. “It controls hellhounds.” 

Dean made a sound somewhere between a laugh and a sigh. “You don’t say.” 

A sound from the side of Sam’s desk interrupted them. It was a notification from an old cell phone, one neither of them expected to ring. 

“One new message,” Sam said, glancing at the screen. 

“Give it here,” Dean said. Sam raised an eyebrow. “You go put the whistle away. We can worry about it later.” Dean’s expression became serious. “If someone’s calling Bobby’s phone, it’s _gotta_ be important.” 

Sam conceded Dean’s point and tossed him the phone, leaving his room to stash the whistle safely away. Dean listened to the message, analyzing every word, pushing their New York excursion from his mind: it wasn’t something he’d soon forget, but their problems were here, and it was, quite literally, a world away.

**Notes for the Chapter:**

> Thank you so much for sticking with me through this whole story (and ~~my~~ Crowley's horrible references)! I hope you enjoyed it! :)


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